Dynamic hyperfine interactions in 111In-doped In2O3 revisited: PAC experiments and ab initio theoretical support

E.L. MUÑOZ; L. A. ERRICO; A. W. CARBONARI; M. RENTERÍA

Beijing

Conferencia; 4th Joint Meeting of the 16th International Conference on Hyperfine Interactions & 20th International Symposium on Nuclear Quadrupole Interaction; 2012

HFI/NQI2012

In this work, we report recent Time-Differential gamma-gamma Perturbed-Angular-Correlations (PAC) experiments performed on 111In-diffused In2O3 polycrystalline samples in order to revisit the dynamic hyperfine interactions reported in the literature at 111Cd impurity sites in this semiconductor oxide [1,2] and to investigate in more detail their origin and possible dependence on the local symmetry of each crystallographic site of the bixbyite structure. These dynamic hyperfine interactions are attributed to the electronic relaxation processes that occur after the electron-capture (EC) decay of the 111In(111Cd) nuclei, usually called (ruffle speaking) after effects. This type of dynamic interactions, using 111In as parent isotope of the 111Cd probe atom,  have been observed  selectively in bixbyite oxides depending if the cations have closed shells (as In, Sc, and Y [1-3]) or partially filled 4f shells (as almost all the lanthanides), in which only static interactions were found [4]. The PAC measurements were performed in air as a function of temperature in the range 10-900 K. The R(t) spectra presents strong damping when measured at intermediate temperatures (150-500 K). This damping decreases partially in the range 10-150 K and totally at high temperatures (500-900 K), where static electric-field gradients (EFGs) are only present. The spectra were fitted with a dynamic perturbation factor proposed by Bäverstam and coauthors [5].  The experimental results are compared with ab initio electronic structure calculations in Cd-doped In2O3 using the Wien2K code [6]. A scenario based on the EFG dependence on the charge state of the Cd impurity [7], supported by the ab initio calculations, is proposed to explain the origin and characteristics of the dynamic hyperfine interactions observed in these experiments.References[1] A.G. Bibiloni, C.P. Massolo, J. Desimoni, L.A. Mendoza-Zelis, F. H. Sanchez, A.F. Pasquevich, L. Damonte and A.R. Lopez-García, Phys. Rev. B 32 2393 (1985).[2] S. Habenicht, D. Lulascu, M. Uhrmacher, L. Ziegeler. K.P. Lieb y ISOLDE collaboration, Z. Phys. B 101, 187 (1996).[3] A. Bartos, K.P. Lieb, A.F. Pasquevich, M. Uhrmacher e ISOLDE collaboration, Phys. Lett. A 157, 513 (1991).[4] J. Shitu, D. Wiarda, T. Wenzel, M. Uhrmacher, K. P. Lieb, S. Bedi, and A. Bartos, Phys. Rev. B 46, 7987 (1992).[5] U. Bäverstam, R. Othaz, N. De Sousa and B. Ringström, Nucl. Phys. A 186, 500 (1972).[6] L.A. Errico, M. Rentería, G. Fabricius and G.N. Darriba, Hyperfine Interactions 158, 63 (2004).[7] E.L. Muñoz, D. Richard, A.W. Carbonari, L.A. Errico and M. Rentería, Hyperfine Interact. 197, 199 (2011).